In large wheel loaders, for instance, a cab is disposed at a high position and a walkway as a communication path to the cab is disposed below the cab. Further, a ladder device is disposed between the walkway and the ground. For example, the ladder device herein employed is either a stationary ladder devices fixed to a vehicle-side member or a movable ladder device configured to be pivoted between a retracted position and a deployed position in usage.
The movable ladder device includes a ladder main body having steps. The ladder main body is pivotable up and down between a deployed posture in usage and a retracted upright posture while the upper end thereof is pivotably supported by a vehicle-side member.
For example, Publication of Japanese Translation of PCT International Application No. JP-A-2008-546576 describes an example of the aforementioned movable ladder device. The ladder device described in the above mentioned publication will be explained with reference to FIG. 13. The ladder device illustrated in FIG. 13 includes a ladder main body 60, a pair of hand railings 61 disposed on an upper part of the ladder main body 60 and a pair of right and left actuation cylinders 62. The hand railings 61 are fixed to a vehicle body. Further, the ladder main body 60 is pivotable between the deployed posture and the retracted posture in conjunction with actuation of the pared right and left actuation cylinders 62. Specifically, the ladder main body 60 is pivoted in the counterclockwise direction in FIG. 13 in conjunction with extension of piston rods of the actuation cylinders 62. Thus, the ladder main body 60 can be retracted. By contrast, the ladder main body 60 is pivoted in the clockwise direction in FIG. 13 in conjunction with contraction of the piston rods. Thus, the ladder main body 60 can take the deployed posture. FIG. 13 illustrates a transitional state of the ladder main body 60 shifting from the deployed posture to the retracted posture.